/**
 * #      828
 * 名称   统计子串中的唯一字符
 * 链接   https://leetcode-cn.com/problems/count-unique-characters-of-all-substrings-of-a-given-string
 * 题解   [40](https://leetcode-cn.com/problems/count-unique-characters-of-all-substrings-of-a-given-string/solution)
 * 通过率 46.5%
 * 难道   困难
 */

